Focusing device for electric lamps



June 23, 1925 1,543,271

r E. s. K. ANDERSON FOCUSING mzvxcx FOR ELECTRIC mars Filed Mai 31, 1921 ners'an Patented June 23, 1925 UNITED STATES PATENTOFFICE."

ERNST GQ-K. ANDERSON, OF CHICAGO, ILLINOIS, ASSIGNOR', BY MESNE ASSIGNMENTS, I TO AIPLETON ELECTRIC 00., OF CHICAGO, ILLINIOS, A CORPORATION OF ILLINOIS.

y rooosme DEVICE roe meme mmrsii Application filed May 31, 1921. Serial' no, 473,647,

To all whom it may concern:

. Be it known that I, ERNEST G. K. ANDER- SON, a citizen of the United States, and a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Focusing Devices for Electric Lamps; and I do hereby declare that the following is a full, clear, and exact description thereof, reference be ing had tothe accompanying drawings, and to the characters of reference marked thereon, which form a part of this specification.

This invention relates to improvements in focusing devices for lamps designed to give axial movement to an electric lamp for the purpose of accurately focusing it with respect to the focal axis of the. reflector of a lamp casing and for locking the lamp in adjusted focal positions. The invention is herein shown as adapted to be a universally directable spot lamp but is capable of general use where like conditions prevail.

The object of the invention is to provide an exceedingly simple and economical device for the purpose set forth whichis made of. few simple parts; which is constructed so as to permit focal adjustment of the lamp without interferingwith the operation of the lamp structure or its mounting, and to otherwise simplify and improve focal adjusting devices for the general purpose set forth.

In the drawings:

Figure 1 is a side elevation, with parts broken away, of a spot lamp equipped with a focus adjusting device embodying my invention.

Figure 2 is a plan View of the parts, shown in Figure 1, with other parts broken away.

Figure 3 is a plan view of the rearwardlv extending stem of the lamp casing, showing parts of the focusing device in plan view.

Figure 4 is a transverse section on the line 44 of Figure 1.

As shown in said drawings, 10 designates a portion of the lamp casing and 11 the usual electric lamp bulb adapted to be arranged in the focal axis of a reflecting or mirrorized surface of the casing or a part carried thereby. 13 designates a'stem which extends rearwardly from the lamp casing to constitute a handle by which the lamp can be directed. Said stem is enlarged and inr ternally threaded at its forward end 14 to engage an externally threaded stud 15 of a plate 16, that conforms to and is fixed to- 20, part of the universal mounting of the lamp, the parts being made hollow to receive the lamp cord 21. In practice, the

controller switch for the lamp circuit can be located in said stem, comprising, in part, the conductors 22, 23, that are connected to the socket terminals. Such a switch is shown in, my companion application for United States Letters Patent filed on the 25th day of June, 1921, Serial Number 480,347, and is a switch mechanism adapted to be exteriorly operated by an actuator member 24. V The said stem 13 is provided on its upper side near the lamp casing with a thickened portion or boss 25 which is cut away to provide a narrow slot 26, said slot being located over the rear end of'the socket 17 and elongated in the direction of the axis of the socket. 27 designates a plate which is supported on the pad 25 and is slidable towards and from the lamp casing. The said plate is shown as held laterally in place on the pad by means of downwardly extending flanges 28 that embrace the sides of the boss. The plate is provided in line with said slot 26 withan opening to receive a screw 29. Said screw is formed at its top with a slotted head 30 and the threaded shank of the screw extends with a close fit through the opening in the cover plate 27 and through the slot 26 of the boss and has screw threaded engagement with the lamp socket 17. As herein shown, the threaded connection of said screw with the socket embraces threads formed partly in the cylindric wall of the socket and partly in a recess 31 in the rear end wall of the socket.

With the parts shown as assembled in socket and the lamp from axial movement. When the screw 29 is released or loosened the lamp socket and the base and lamp carried thereby. can be adjusted length-Wise oi the stem 13 SO as to move said lamp into proper focal relation to the axis of the refiector, the slot 26 being made of suflicient length to permit ample movement of the socket for this purpose. iVhen the parts are thus shifted, after loosening the screw, the" cover pl'ate27 also moves: with the screw, h qh iwan'nowv e sily do, y r as n r he release of friction between the plate and ba i n e] o rlai f th cover plate beyond the ends of the slot is sufliciently great to maintain the said slot always covered throughout any required movement of the parts associatedwith said screw to bring the lamp in proper focal relation to the refiectorQ V Vilhen the focal adjustment has been fixed a h "se 29 sti rn'ed i h ly dow 1. the cover plate 27,]the efliect of thetightening of the. screw has three important functions, first, itlocks the socket andthe lamp base ca d he eb xedly nv p sitio o free from longitudinal movement in the stem 3 second, the drawing of the socket and the cover plate, which latter possesses some springiness or'deformab-ility, toward each other through the action of the screw 29 serves,in the manner of a lock to hold screw from turning backwardly and, third, the said screw serves as a means to fixedly hold the cover plate 27 down over theslotted portionoiftheboss and to thereby provide a water proof joint which will prevent the entrance of dust or the elements into the interior ofthez shank or st'em 13 Thus it. will be seen that when the focal adjustment is. made it willbe reliably maintained through the action oi the screw that. is threaded into the socket and bridged across the slot 26 between the socketand cover plate. It, isalso to be observed that the. focal, adjustment may bevquickly, and readily made with the use of, a, simple tool, as a screw driver, by inerely slacking the screw 30, moving-the cover plate and screw in the direction desired, which carries with it-the socket and-the lamp, and afterwards tightening the screw toltacl; the parts in place, This, adjustment can be n a dewithout in any manner derangingithe other parts ot the lamp or modifyingthe iiu-nction of the lamp.

The flanges-28 of the cover plate serve as means to' prevent twisting movement of the cover plate on the pad'25 and. aidsin hp ing said cover plate in position, to at all times, cover the slot- 26 to prevent entrance of foreign matter therethrough into the hollow shank or stem and in contact with the terminals between the lamp case and the contacts of the socket throughfwhich current is carried to the lamp iiilni. Furthermore, the width of the slot 2Gi's such, with respect to the diameter of the screw, 29, that said slot constitutesa guide for the screw. an'd'the depth of the 'uide slot isisucl' a s to provide a wide bearing between the sides of 'the slot and said screw. The parts arethns held in fixed guiding relation, even' when the screw is slacked to permit lamp focal adjustment of the lamp bulb. i

It will be understood that the structural detailsoi' the invention shown and described may be somewhat varied withoutdep'arting from the spirit of the inrent-ion or sacrific ing the advantages ofthe illustrated embodiment, and that the, invention is not limited to said details shown, ex'ceptf'asto parts which are herein made the subjectot a; specific claim, and as imposed by the prior art. v

I claim as my invention;

A focusing device forelectric lamps comprising, in combination with 'the re'fiector of a lamp, a tubular member coaXia'lwith the focal axis of thereiiect'or h'aving an intermediate depending pivotal support divid? ing'said member into a ibrward lam p supporting portion and a rearward handle portion, a'i' ocall adjustment member telesco'pie cally slidable in the end 01"." said forward portion and provided at its inner endwitli means for the attachment-to a lamp socket, said forward portion being providedwith an elongated slotted boss, a laterally flanged plate forming a cover over-said slotted boss; and an adjustable locking device passing through said cover plate and extending through said'slot'into said focal adjustment mem r v i In witness whereofI claim the foregoing as my invention, l hereunto append my signature this27 day of May, 1921,

ERNST G; K. ANDERSUN. 

